KrisD
Intuit Alumni

After you file

Yes, you will need to add her financial information on the 1040X since you are both considered one taxpayer when filing Married Filing Jointly (MFJ). 

According to the IRS:

"You are changing from separate to a joint return. If you and your spouse are changing from separate returns to a joint return, follow these steps.

Enter in column A the amounts from your return as originally filed or as previously adjusted (either by you or the IRS).

To determine the amounts to enter in column B , combine the amounts from your spouse’s return as originally filed (or as previously adjusted) with any other changes you or your spouse are making . If your spouse didn’t file an original return, include your spouse’s income, deductions, credits, other taxes, etc., in the amounts you enter in column B.

Read the instructions for column C to figure the amounts to enter in that column.

Both of you must sign and date Form 1040X."

CLICK HERE for IRS information about Amended Returns

https://ttlc.intuit.com/replies/3300283

[Edited 02.25.2018 | 10:02 AM]